<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
  </head>
  <body>
    <style>
      article {
        display: flex;
      }
      article > div:first-of-type {
        /* margin-right: auto; */
        /* flex-grow: 1; */
        flex: 1;
      }
    </style>
    <article>
      <div>菜单</div>
      <span>user</span>
    </article>
  </body>
</html>
